rebecca,
Since Phyl is tossing my name around, let me offer my two cents on what I have seen written on Protons.
There is no such thing as the "ultimate radiation" , I would classify that as marketing hype. All radiation works the same on the tumor whether it's source is cobalt ( GK) , linear accelerator ( CK and others) or proton. Collateral damage is a function of the delivery accuracy of the machine, not the type of radiation. In that regard, CK , to my knowledge is still the best based on clinical studies (.89mm) with GK slightly higher at 1.2-1.5 mm. The alleged advantage of Protons is that they hit the tumor and stop whereas X-rays pass through. However, the amount of dosage in the X-rays is designed to be so low in individual beams which do not cross as to minimize impact on healthy tissue. Proton machines are hugely expensive , usually 4-5 times a CK unit ( $20-25M vs $5-7M) but have to date not shown any enhanced efficacy in terms of outcomes compared to the other machines, yet as the Post from Dr. Medbery showed in clinical studies it does seem to have a higher level of complication. I will offer another post from Dr. Medbery on his view of Proton and I find the closing comment to be quite illuminating so I'll highlight it.
PRotons have not been shown to be superior for any tumor. They are probably as good for certain things such as clivus chordomas etc, but they have not been shown to be superior or even as good as CK or GK for AN. In fact, MGH reported ontheir series in 2003:
RESULTS: The actuarial 2- and 5-year tumor control rates were 95.3% (95% confidence interval [CI], 90.9-99.9%) and 93.6% (95% CI, 88.3-99.3%). Salvage radiosurgery was performed in one patient 32.5 months after treatment, and a craniotomy was required 19.1 months after treatment in another patient with hemorrhage in the vicinity of a stable tumor. Three patients (3.4%) underwent shunting for hydrocephalus, and a subsequent partial resection was performed in one of these patients. The actuarial 5-year cumulative radiological reduction rate was 94.7% (95% CI, 81.2-98.3%). Of the 21 patients (24%) with functional hearing (GR Grade 1 or 2), 7 (33.3%) retained serviceable hearing ability (GR Grade 2). Actuarial 5-year normal facial and trigeminal nerve function preservation rates were 91.1% (95% CI, 85-97.6%) and 89.4% (95% CI, 82-96.7%).
If I were getting that kind of toxicity with CK I'd slit my wrists.
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Clinton A. Medbery, III, M.D.
St. Anthony Hospital Cyberknife Center
(405) 272-7311
buddy@swrads.org